The present invention relates to an electric accumulator battery, of the lead-acid type, employed, for example, in the starting, lighting and semi-traction of motor vehicles.
More specifically, the battery of the invention refers to a battery of the conventional type or of the recombination type, which comprises a receptacle generally prismatic in form, closed at the top by means of a cover through which project the connection terminals, the receptacle being internally subdivided into cells, preferably more than six cells, in which are housed insulated positive and negative electrodes with intermediate separators.
The present evolution of motor vehicles towards increasingly sophisticated internal and external fittings and the need to economise in the investment required to produce such motor vehicles, is producing an increasing demand for electric power on board the vehicle, which signifies recurring more and more frequently to the battery and an ever-growing demand for power which in turn needs a cable of greater cross section and which also discharges the battery much more deeply, leading to a considerable reduction in battery life.
The conventional design of the batteries employed as power source in motor vehicles is presently standardised in the coupling of six series-connected elements, each one of which has a determined number of positive and negative electrodes connected in parallel and physically separated by a porous material, which permits the free circulation of the ions that intervene in the electrochemical reactions of charging and discharging.
Due to the growing demands of the automobile manufacturers with regard to increasing power, while respecting or even reducing the outside dimensions, the battery manufacturers find themselves obliged to increase the number of electrodes per element, by reducing their thickness, since the standard rated voltage is 12 Volts and the total dimensions must also be respected. The reduction in electrode thickness leads to a reduction in service life, due generally to the destructive effect of the corrosion of the grids that act as holders of the active material of the electrodes and as conductors of the electric current produced. As a consequence thereof, the 12 Volt batteries designed to supply high power levels have a very limited duration in cycle life and give rise to premature failures under the most extreme conditions demanded by modern vehicles.
The objective of the present invention is a battery which permits maintaining of suitable dimensions within the internal architecture of the vehicle in which it is to be equipped and provision of the high power required, greater than the 12 Volts which have been standardised up to now.
Some motor vehicle manufacturers are calling for studies to achieve the use of batteries with a nominal voltage of more than the 12 Volts rated and standardised up to now, with the condition that either the standardised outside measurements be maintained or the dimensions be suitable for the compartment available in the vehicle for holding the battery; more specifically, the motor vehicle manufacturers wish to have batteries rated at 36 Volts, for the principal objective of assuring the starting operation, since the current necessary to start the vehicle would be around one third of that presently required, and with the additional objective of economising on the cost of the main cabling, whose cross section would be reduced in line with the rise in voltage.
The design of a 36 Volt battery can be made, according to the present invention, by means of joining in series 18 elements having electrodes that can be flat or of another type, like for example, spiral in form, in which the increase in electrode surface area is limited by the internal geometry of each element and by the thickness of the plates and separators.
Manufacture of 12 Volt batteries is standard practice and consequently it would only be necessary to connect three batteries in series to achieve a 36 Volt battery. The present invention refers to a battery of more than 12 Volts, generally 36 Volts in a single receptacle, which is also adapted to fit in the compartment allowed by the manufacturers of modern motor vehicles.
On the other hand, the manufacture of a battery of more than 12 Volts in a reduced space means the elements have to be mounted up against each other, resulting in thermal differences because of the difficulty of achieving uniform cooling; it is well known that the high temperature caused by the vehicle engine has a strong influence on battery lifetime due, among other reasons, to the greater concentration of electrolyte produced by the greater evaporation of water because of the increased temperature, due also to the higher charging current occurring when the vehicle is running, which in turn is the cause of an overcharging effect whereby a greater quantity of the water held in the electrolyte is decomposed, which in turn leads to premature deterioration of the battery; thus the elements that are least exposed to the cooling effect deteriorate before those receiving better cooling and cause the premature destruction of the unit, even though there are other elements which remain unharmed.
The purpose of the present invention is to achieve a battery which, having a rated voltage greater than 12 Volts, generally 36 Volts, is housed either in a standard normalised size for use in motor vehicles, or else has a size adequate for the space requirements in the motor vehicle interior, with the condition that it be capable of maintaining cooled the front cells or elements to prevent the thermal differences that result in premature battery failure.
To this end, in accordance with the invention, the battery receptacle is internally subdivided into six cells and preferably into ten and eight cells, which shall be distributed in two parallel rows between which the receptacle forms one or more intermediate voids, which penetrate through the base and cover and constitute ventilation ducts.
Moreover, the cover of the receptacle, on two of its opposite edges, below the upper surface of said cover, forms cavities which are of a size that permit the fingers to be inserted and serve as grips that facilitate battery handling and transportation.
The aforementioned characteristics and advantages can be more easily understood through the following description, made with reference to the attached drawings, in which an embodiment is shown in a non-restrictive manner.